Our objective is to study the characteristics of the following animals: earthworms, cockroaches, bony fish and birds.
Furthermore, for each specimen we need to identify:
Animals are multicellular organisms that are made up of eukaryotic cells and come under the kingdom Animalia. They have a well developed sensitive nervous systems and the ability of locomotion. Animals need to ingest other organisms, or their products, for sustenance because they do not perform photosynthesis.
Animals are adapted to the conditions of the habitats in which they live. There are three major types of habitat:
Animals also depend on their physical features to help them move about, obtain food, and keep safe. These physical features are called physical adaptations. Based on their physical characteristics, the Kingdom Animalia is divided into two sub-kingdoms:
Invertebrates are animal species that do not have a backbone or spinal column. This, in effect, includes all animals apart from the subphylum Vertebrata. Some common examples of invertebrates include insects, worms, clams, crabs, octopus, snails, and starfish.
Vertebrates are animal species that have a backbone or spinal column. These include jawless fish, bony fish, sharks and rays, amphibians, reptiles, mammals, and birds.
Shown below is a broad classification of the animal kingdom.
We will now look at the characteristics of some animals based on their phylum and adaptations.
Phylum: Annelida; Habitat: Subsoil (Terrestrial)
The earthworm has a long cylindrical body that is covered by a moist, protective cuticle. The body of an earthworm is segmented and these segments are called Annuli. The body wall has three cell layers- ectoderm (outer layer), mesoderm (middle layer) and endoderm (inner layer).
The Clitellum is a thickened glandular section of the body wall in earthworms and leeches that secretes a viscid sac in which the eggs are deposited. The body wall has a moist secretion that makes the skin slippery and moist so that soil does not stick to the skin. All annelids except leeches have tiny hair like bristles called setae, projecting from their cuticle.
The setae are composed of chitin. It is the setae that help the earthworm to attach itself to the ground and prevent it from sliding back during peristaltic movement. The body is flexible, as it has no skeleton. At one end is the mouth which is covered by a flap, called the prostomium. The prostomium helps the earthworm sense light and vibrations, as it has neither eyes nor ears. At the other end is the anus through which waste is excreted.
Specific features of Phylum Annelida
Phylum: Arthropoda; Habitat: Terrestrial
A cockroach has an externally segmented body divided into three main parts- the head, thorax and abdomen. Its body is protected by an exoskeleton of a thick cuticle made of chitin. The head bears compound eyes that allows the cockroach to see simultaneously in all directions. It has a pair of long antennae that helps it to smell.
The thorax has three segments. Each segment bears a pair of jointed lateral appendages that helps it in movement. The last two segments of the thorax have two pairs of wings which help it to fly short distances.
It has holes, called spiracles, in its thorax and abdomen to take in atmospheric oxygen. There are two wind sensitive hairs called cerci on the last segment of its body. These act as a warning system against its enemies. A flattened body allows it to creep into very narrow crevices. Cockroaches are omnivorous and are nocturnal. They come out of their hiding places at night in search of food.
Specific features of Phylum Arthropoda
Phylum: Chordata; Subphylum: Vertebrata; Class: Pisces; Subclass: Osteichthyes; Habitat: Aquatic
Bony fish are found in marine and fresh water. They have a stiff bony skeleton and like all fishes, their heart is two chambered.
A streamlined body helps in movement by cutting through water easily. It has fins that helps it to change directions in its movement. The body is covered with scales that help prevent decay from water.
Gills on the either side help to breathe in air. A flap called operculam on each side of the head covers the gills, and allows air to enter the gills. The internal air sac or air bladder makes the fish more buoyant and keeps it afloat. It senses pressure of water with the lateral line system, a special sense organ, which enables it to 'touch' objects at a distance.
A muscular tail extends backward behind the anus. Fishes are cold blooded aquatic animals.
Specific features of Phylum Chordata (Class: Pisces)
Phylum: Chordata; Subphylum: Vertebrata; Class: Aves; Habitat: Aerial
A bird is adapted for an aerial habitat, as it has wings and feathers. It is also adapted to land, as it is bipedal (two rear limbs). Birds are warm blooded and their body is divided into the head, neck and trunk. The trunk is divided into the thorax and abdomen.
A bird has a strong skeleton. Birds have pneumatic bones that are hollow, and light in weight. This feature enables them to fly in air. Furthermore, a streamlined body also helps it to cut through air. The forelimbs are modified into wings which enable it to fly. The hind limbs are long and have toes and claws, which help to hold food, and hold onto branches.
Birds have a four chambered heart and well developed lungs that have air sacs attached to them. The air sacs help birds in respiration. The upper and lower jaws are modified into a horny beak without teeth. Birds have a large muscular stomach and are oviparous, that is they lay yolked, hard-shelled eggs.
Specific features of Phylum Chordata (Class: Aves)
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